1OF8: Double Complex Of The Tyrosine Sensitive Dahp Synthase From S. Cerevisiae With Co2+, Pep And The E4p Analogoue G3p

3-Deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthases are metal-dependent enzymes that catalyse the first committed step in the biosynthesis of aromatic amino acids in microorganisms and plants, the condensation of 2-phophoenolpyruvate (PEP) and d-erythrose 4-phosphate (E4P) to DAHP. The DAHP synthases are possible targets for fungicides and represent a model system for feedback regulation in metabolic pathways. To gain further insight into the role of the metal ion and the catalytic mechanism in general, the crystal structures of several complexes between the tyrosine-regulated form of DAHP synthase from Saccharomyces cerevisiae and different metal ions and ligands have been determined. The crystal structures provide evidence that the simultaneous presence of a metal ion and PEP result in an ordering of the protein into a conformation that is prepared for binding the second substrate E4P. The site and binding mode of E4P was derived from the 1.5A resolution crystal structure of DAHP synthase in complex with PEP, Co2+, and the E4P analogue glyceraldehyde 3-phosphate. Our data suggest that the oxygen atom of the reactive carbonyl group of E4P replaces a water molecule coordinated to the metal ion, strongly favouring a reaction mechanism where the initial step is a nucleophilic attack of the double bond of PEP on the metal-activated carbonyl group of E4P. Mutagenesis experiments substituting specific amino acids coordinating PEP, the divalent metal ion or the second substrate E4P, result in stable but inactive Aro4p-derivatives and show the importance of these residues for the catalytic mechanism.
PDB ID: 1OF8Download
MMDB ID: 27557
PDB Deposition Date: 2003/4/8
Updated in MMDB: 2005/11
Experimental Method:
x-ray diffraction
Resolution: 1.5  Å
Source Organism:
Similar Structures:
Biological Unit for 1OF8: dimeric; determined by author and by software (PISA)
Molecular Components in 1OF8
Label Count Molecule
Proteins (2 molecules)
Phospho-2-dehydro-3-deoxyheptonate Aldolase, Tyrosine-inhibited(Gene symbol: ARO4)
Molecule annotation
Chemicals (8 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB